#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main()
{
  //close(0);
  //close(2);
  //close(1);
  

  umask(0);
  //int fd =open("log.txt", O_WRONLY | O_CREAT | O_TRUNC, 0666);
  //int fd =open("log.txt", O_WRONLY | O_CREAT | O_APPEND, 0666);
  int fd =open("log.txt", O_RDONLY);
  if(fd < 0)
  {
    perror("open");
    return 1;
  }

  dup2(fd, 0);//输入重定向

  char line[64];

  while(1)
  {
    printf(">");
    if(fgets(line, sizeof(line),stdin) == NULL) break; //stdin ->0
    printf("%s",line);
  }

 // if(dup2(fd, 1) > 0)
 // {
 //   ;
 //   //close(1);
 // }

 // printf("open fd: %d\n",fd);//printf ->stdout
 // fprintf(stdout, "open fd: %d\n",fd);//printf-> stdout

 // const char* msg = "hello world\n";
 // write(1,msg,strlen(msg));

 // fflush(stdout);

  close(fd);

  return 0;
}
